Author of The Profession of Violence: the rise and fall of the Kray Twins, he exposes another chillingly amoral world in this book. During the 1950s, Aspinall plied a meagre trade behind London's Oxford Street as an illicit backstreet bookie. Yet, within a decade, he had moved over to Mayfair to found the most exclusive - and profitable - gaming rooms in Europe. The leap in Aspinall's status lies in the Clermont Club's membership, the most valued members being the British aristocracy, preferably rich and so addicted to gambling that, like the trustee Ian Maxwell Scott, they could take a bet on two drops of rain running down a window pane. Aspinall knew how to coax and flatter the gentry and, more importantly, he provided the sort of surroundings at 44 Berkeley Square where the descendants of Regency gamblers could enjoy themselves in a world that they thought they had lost.

The Clermont wasn't merely a nostalgic setting in which to fleece the idle rich. Among its members were such cold-eyed cardsharps as Jimmy Goldsmith, a club co-founder, billionaire "casino capitalist" and world-class backgammon player, and Gianni Agnelli, the head of Fiat who took £200,000 off the Earl of Derby in a single night of chemin de fer. Aspinall himself had a natural affinity for gambling. Not only did he have prodigious powers of concentration, he possessed nerves of steel and a precisely calibrated sense of risk. Aside from gaming skills, though, there is a distinct dividing line between those who gamble and those who live off gamblers.

Through the 1960s, Aspinall, Goldsmith and the other owners of the Clermont acted as Pied Pipers of gambling. And, in order to encourage gullible punters to keep trying their luck, the club hedged its bets. It employed "House" players, usually old Etonians paid £10 a week, to ply the upper-class clientèle with drink and keep them playing until they were totally cleaned out. One of the heaviest losers was "Lucky" Lord Lucan, a dim reactionary whose favourite reading in the early hours after retiring from the tables was Hitler's Mein Kampf.

His skewed value system and hypocritical sense of "fair play" gave Lucan an instant affinity with the Clermont Set. At the point of the drunken peer's introduction, two-thirds of the way into Pearson's riveting book, it has to be admitted that one wants to be rid of this overbearing, disdainful cast of characters. But Pearson cleverly switches from a group biography into a murder mystery and, because he concentrates on Lucan's disappearance, rather than the more well-known facts about the killing of the nanny in the Belgravia basement, he entices the reader into a whodunnit. The gripping depiction of this amoral hierarchy sets John Pearson's book apart from others on the Lucan case.